Use to shoot sharks with an M1 Garand on the flats near Key West.
In Saudi Arabia in the Red Sea used CO2 tipped spear, (like a hypodermic needle) to kill Black tip reef sharks. You pierce them, CO2 is released, inflates them and they rise to the surface where other sharks would go into a feeding frenzy tearing them apart. We were group called "guerrilla divers".
Here is a Hammerhead I took with speargun off of Ajman, UAE. Spearguns are illegal there, but if you are friends with the local Sheik, no problem. It was his speargun. I make potato guns for these guys. They fire them mortar like over the 20 foot walls of their palace on to the poor peasants in the the open air market, and fire them from the deck of their yachts on to the poor peasants on the beach.